Temperature responsive device



June 1942- J. M. BRIAN 2,287,289

TEMPERATURE RESPONSIVE DEVICE Filed June 29, 1939 awe/whom JEJsep/v M Brian.

Patented June 23, 1 942 UNITED STATES PATENT OFFICE TEMPERATURE RESPONSIVE DEVICE Joseph M'. Brian, Linthicum Heights, Md assignor, by meme assignments, to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application June 29, 1939, Serial No. 281,985

3 Claims. (Cl. 297-15) This invention relates to electrical apparatus, responsive variable condenser in which the rate and more particularly to thermostatically conand degree of capacity variation with respect to trolled condensers for compensating for the eftemperature may be. readily adjusted. fects of temperature variation on the component Other objects and advantages will in. part be elements of a tuned circuit. 5 specifically stated and in part be obvious when In radio and allied fields which employ oscil the following specification is read in connection latory currents of high frequency, the mainwith the drawing, in which:

tenance of a particular frequency is exceedingly Fig. l is a front elevation of the invention; and

important, and allowable frequency drift is con- Fig. 2 is a top plan view.

fined to very close tolerances. One of the pre- Referring in more detailto Fig. l, the numeral dominant causes of frequency drift in tuned cirl indicates a mounting base upon which a bracket cults is a change in the circuit characteristics 2 supports a variable condenser 3 of the interat different levels of temperature. As a tube leaving plate type. The condenser maybe a well heats, the inter-electrode capacities change known midget" size which is commercially values. The coils and other components are available and comprises a ceramic base 4 which heated by radiation from the tubes and by a is attached to the bracket 2 by screw fastenings general rise in the ambient temperature under I and C. The stator bars I and 8 extend from operating conditions, thus producing thermal the ceramic base and carry the stator plates 9.

expansion of the components and varying dis- A rotatable shaft l0 extends through the base 4 tributed capacity relations and circuit tuning and carries the rotor plates ii in interleaving generally. All of these variable factors conrelation to the stator plates. As best seen in tribute to change the frequency to which the Fig. 2, a block i2 is fixed to the forward end of circuit may be resonant. By good design practices shaft II, and is bored to receive the laterally such frequency shifts may be kept fairly small, extending arm i3. Adjustably mounted on the but in many instances a higher degree of prgarm I: is a collar I. A bimetallic strip l5 has cision is required. In such cases a thermoone end resting on the upper surface of the statically controlled variable condenser of small collar and a set screw Ii passes through an opencapacity may be connected in the tuned circuit ing, which may be in he f of slot. in the in such manner that its value changes in oppostrip to secure the collar it in desired position site sense to other changing values of the ciron the arm il- The end of the strip i5 is recuit, and so stabilize the overall constants of the tained snugly against the collar by a compression circuit. Previous condensers of this type have spring I whi h a s a a nst t h ad of the generally comprised aligned parallel plates, one set screw IS. The other end of the bimetallic of which is moved toward the other by thermorip I5 is e ur d to the flattened top of a P static action. One big disadvantage of such condensers is that the change of capacity is not the mounting base I The post ll (Fig. 1) has a linear with temperature and such a relation is reduced shank portion is which passes through a frequently desirable in practice. Another disadspacing spool 20 and the base I. A collar ii is vantage has been that the capacity rate of change mounted on the P jectin end of the Shank per degree of temperature change could not 40 and it maybe dr p tightly and Secured With readily be modified to suit changing circuit rethe set screw 22 to hold the post It and biquirements. The invention to be later described m llic S rip l5 in esi ed angular P i noifers a solution to both of the foregoing dim- It will be obvious that many changes and oulties. modifications may be made by anyone skilled in One object of this invention is to provide a the art without departing fro e p r and condenser which varies in capacity in response scope of the invention as defined in the following to changes of temperature. claims. v

' Another object is to provide a temperature re- What is claimed is:

sponsive variable condenser in which the range 1. In a thermally responsive device, a driven of operation may be more easily and accurately element having a rotatable shaft, an arm atcontrolled. I tached to said shaft and projecting laterally Another object is to provide a temperature retherefrom, a bimetallic strip comprising a strip sponsive variable condenser which employs standof one metal secured to a strip of a dissimilar ard and readily available constituent parts. metal at a plurality of points over their com- A further object is to provide a temperature mon length, the interface between the two metals 5 II which is angularly adjustable with respect to defining a plane surface at a predetermined reference temperature, means for mounting said bimetallic strip with said interracial plane substantially parallel to the axis of rotation of said shaft and for rotating said bimetallic strip about an axis substantially perpendicular to said axisof rotation of said shaft and to said interfacial plane and parallel to the plane determined by the thermally produced movement of said himetallic strip, and means providing a driving coupling between one end of said bimetallic strip and said arm.

2. In a thermally responsive device, a driven element having a rotatable shaft, an arm attached to said shaft and projecting laterally therefrom, a bimetallic strip comprising a strip of one metal secured to a strip of a dissimilar metal at a plurality of points over their common length, the interface between the two metals defining a plane surface at a predetermined reference temperature, means for'mounting said bi- 'metallic strip with said interfacial plane sub plane and parallel to the plane determined by the thermally produced movement of said himetallic strip, and means adjustable along the length of said arm for coupling one end of said bimetallic strip in driving relation to said arm.

3. In a thermally responsive device, a driven element having a rotatable shaft, an arm attached to said shaft and extending laterally therefrom, a post angularly adjustable about an axis substantially perpendicular to the axis of rotation of said shaft and parallel to the plane of rotation of said arm, a bimetallic strip comprising a strip of one metal secured to a stripof a dissimilar metal at a plurality of points over their common length, the interface between the two metals defining a plane surface at a predetermined temperature, means for securing one end 01' said bimetallic strip to said post with said interfacial plane substantially parallel to the axis of rotation of said shaft and perpendicular to said axis of angular adjustment of said post, and means providing a driving connection between the other end of said bimetallic strip and said arm. JOSEPH M. BRIAN. 

